AUTOMATIC DEVICE FOR MAGNETICALLY ACTUATED VALVES FOR PRECISION ANALYSIS OF THE ISOTOPIC COMPOSITION OF OIL

N. K. GRIGOR'EV

(Presented by the scientific seminar of the Geological Prospecting Faculty)

The inlet system of mass spectrometers of serial production is not adapted for isotopic analysis of substances by the precision method. In view of this, experimenters are compelled to design and manufacture under laboratory conditions an inlet system suitable for these purposes (1, 2, 3, 4).

One of the indispensable units of such an inlet system for precision analysis is the unit of magnetically actuated valves, which makes it possible to introduce alternately into the ion source of the mass spectrometer the working standard and the gas under investigation.

The action (raising and lowering) of the valves, inside the glass cylinder of which an iron core is sealed in, is carried out by means of the magnetic field of solenoids (the construction and operating principle of magnetically actuated valves are described in detail in the work of V. I. Ustinov and V. A. Grinenko [4]).

Usually the switching of the valves and the opening and closing of the corresponding channel of the inlet system are performed manually, which is not only inconvenient, but also makes it difficult to obtain the same duration of recording on the electronic potentiometer. Therefore researchers try in some way to automate this process.

Thus, for example, in the mass-spectrometric laboratory of the Moscow Institute of Petrochemical and Gas Industry named after I. M. Gubkin, an automatic device is assembled from a small low-speed electric motor connected to a worm shaft, on which a relay is movably mounted, successively switching the solenoids of the magnetically actuated valves.

We have made an automatic device for magnetically actuated valves on the basis of a synchronous electric motor of type SD-2 with a pin switch from the set of the MS-2 mass spectrometer (see Fig. 1). On the shaft of the pin switch a small drum (5) made of textolite is rigidly fixed, which in plan is, as it were, a circle consisting of two sectors of different radius \((R_1 = 5\ \text{mm},\ R_2 = 11\ \text{mm})\). To the housing of the pin switch, next to the textolite drum, a time relay \((P_1)\) is attached, the contacts of which are connected into the electrical circuit of the magnetically actuated valves.

When the electric motor \((M)\) is switched on, the pusher, mounted on the middle contact of the relay, slides over the surface of the drum, alternately closing and opening first the left and then the right parts of the electrical circuit, into which two parallel-connected pairs of sole-

solenoids (1—4 and 2—3). The magnetic field arising in the solenoids raises or lowers the corresponding pairs of valves, opening or closing one of the inlet valves. A cam switch connected to the electric-motor shaft makes it possible to record on the chart with a “working standard—sample” cycle duration of 1, 2, 3, 4, and 5 minutes. During admission of gas from storage ampoules into glass flasks, switch \(B_2\) stops the electric motor, and one of the inlet channels remains open until the electric motor is switched on again.

Fig. 1. Electrical circuit diagram of the automatic device for magnetically actuated valves.
1, 2, 3, 4 — solenoids; \(M\) — electric motor with cam switch; 5—drum; \(P_1\) — time relay; \(L_1L_2\) — signal lamps

The electric motor, the cam switch with a textolite drum, and the time relay are assembled into one compact unit, which is mounted on the right side of the inclined panel of the measuring section of the MI-1305 mass spectrometer.

For automation of the operation of magnetically actuated valves, it is in principle possible to use the automatic equipment of the sweep unit and of the MI-1305 mass spectrometer itself, replacing its wire potentiometer with a drum and adding a time relay. However, in this case a certain difficulty arises because of the long duration of the sweep time—3, 6, 9, 12, and 15 minutes. Therefore we adopted the scheme described above for automating the operation of magnetically actuated valves.

References

1. I. M. Al’berg. A precision method for determining isotope ratios. Geochemical Collection, 8, 1968.

2. E. M. Galimov. Methodology of mass-spectrometric analysis of the isotopic composition of carbonates. Geochemical Methods for the Study of Wells. “Nedra” Publishing House, Moscow, 1966.

3. V. S. Lebedev. Isotopic composition of carbon in oil and gas. Geochemistry, No. 11, 1964.

4. V. I. Ustinov, V. A. Grinenko. A precision mass-spectrometric method for determining the isotopic composition of sulfur. “Nauka” Publishing House, Moscow, 1965.